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MBBS QUESTION #10225
Question 1
A patient with von Willebrand disease presents with mucocutaneous bleeding, a prolonged bleeding time, and normal platelet count. This is best explained by impaired:
  • Platelet adhesion to exposed subendothelial collagen, since von Willebrand factor normally bridges platelet GPIb receptors to collagen✔️
  • Activation of the extrinsic coagulation pathway
  • Platelet production in the bone marrow
  • Fibrinolysis
Correct Answer Explanation
Von Willebrand factor (vWF) mediates initial platelet adhesion to injured subendothelium via the platelet GPIb receptor, and also stabilizes circulating factor VIII. Its deficiency impairs primary hemostasis (prolonged bleeding time) despite a normal platelet count, and can also mildly prolong aPTT due to associated low factor VIII.